During the process of boning a carcass, and particularly a beef carcass such as a steer or cow, the tallow and fat often referred to as “trim” is removed. Other “trim” is cut from primal beef portions during the slicing and disassembly process of carcasses that is required during preparation of small cuts for human consumption. During these processes, a significant amount of lean beef can be cut from the carcass and carried away with the fat and/or tallow. Lean beef comprises predominantly muscle protein although some amounts of fat and tallow are present, while fat and tallow comprises predominantly glycerides of fatty acids with connective tissue and collagen and are the predominant constituents of plant and animal fat. The lean beef content in trim may be as high as 45% to 50% by weight. Presently, trim has little use except for sausage production, or alternatively the fat may be rendered. The value of lean beef in the trim is therefore relatively low compared to boneless beef having a reduced fat content of just 15% by weight, for example. The value of 50% lean beef trim is perhaps in the order of 35 cents per pound compared to perhaps about $1.10 for 85% boneless lean beef. It is therefore desirable to separate the lean beef from the trim so as to reduce the fat content but without increasing the natural proportion of connective tissue and collagen.
In one conventional method to recover the lean beef, the trim can be heated to about 109° F. The heated trim can then be processed in a centrifuge that separates the fat only from the lean beef. For many years, in fact since the earliest point in time when low fat ground beef came into popular demand, beef processing companies have sought methods to effectively separate ground tallow and fat from ground beef. Fat on the one hand is a beef component that comprises a substantial part of tallow. However, tallow includes proportions of fat and collagen with small quantities of connective tissue. If fat alone is removed from ground beef then the proportion of collagen, fat, connective tissue and lean beef will not be the same as the natural proportions. In order to maintain ground beef with natural proportions of lean beef, connective tissue, collagen, and fat, it is desirable that the natural relative proportions of fat, collagen, and connective tissue that comprise tallow are separated proportionately and, in fact, in quantities equal to those contained in tallow. Therefore by separating lean beef from tallow in the manner according to the invention, the natural proportions as required by USDA can be maintained. The method of the invention described herein below is in distinct contrast to the only other method practiced presently in the beef industry. The present invention enables separation of fat from ground beef such that after separation, the lean ground beef portion displays a bright cherry red color preferred by the typical consumer, while said portion of ground beef comprises natural proportions of lean beef, fat, collagen, and connective tissue. The other method briefly described herein, wherein the temperature of the lean beef is elevated to a point where beef fat melts and becomes oil-like, enables separation of the fat and oil only such that collagen and connective tissue, which should be removed with the fat, remains together with the lean beef portion. Following the separation, the method practiced by, for example, BPI of Dakota Dunes, S. Dak., the lean beef that contains a greater proportion of collagen and connective tissue compared with the natural proportions of natural ground beef is then frozen and chipped into small flakes. This finished product, known as lean finely textured beef (LFTB), as herein above explained, is then stored in a frozen condition and can later be added to ground beef. The temperature of the LFTB during the separation process does not exceed the temperature that a carcass would normally experience post mortem. As a result, pathogens and bacteria that are present on the surfaces of the carcass can result in bacteria being present in the LFTB. Additionally, the method of heating and centrifuging requires that the trim be shipped from the beef packing facility to an outside facility and then returned to the packer at a significant expense, and furthermore can also enhance viability and increased population of pathogens.
A need therefore exists to more efficiently separate the lower value tallow with fat from the higher value lean beef contained in trim and to more effectively kill, reduce, or completely remove the microbial pathogen population and to eliminate sources of cross contamination and recontamination. In particular the substantially complete killing of all pathogens, such as E. Coli 0157:H7 that can be present in trim, is desirable, and this can be achieved with the appropriate manipulation of the multiple natural phases of carbon dioxide by exposure of trim thereto, according to the disclosure as set out below.